The present invention relates to a multilayer ceramic substrate for packaging semiconductor devices and similar heat generating devices. More particularly, the invention relates to a multilayer ceramic substrate having cooling channels for cooling a semiconductor device, or other similar heat generating device, placed on the substrate.
Multilayer ceramic (MLC) substrates are used for interconnecting a semiconductor device or similar heat generating device (hereafter collectively referred to as semiconductor device(s)) to the next level of packaging such as a board. The MLC substrates provide wiring circuitry which provides for the transmission of signals and power to and from the semiconductor device. In addition, the typical MLC substrate may provide some level of cooling of the semiconductor device via transfer of heat from the semiconductor device through the MLC substrate. It is more usual to provide some external apparatus, such as a cap and heat sink, to remove heat from the semiconductor device. This external apparatus often has internal channels for the flow of a cooling fluid. Numerous proposals have been made for removing the heat generated by semiconductor devices by such external apparatus.
Edmonds et al. IBM Technical Disclosure Bulletin, 23, No. 3, p. 1057 (August 1980), the disclosure of which is incorporated by reference herein, discloses a heat exchange element having internal cooling channels built up on the back of the semiconductor device. Such an arrangement, of course, makes the semiconductor device very expensive and risks damage to the semiconductor device during processing of the heat exchange element. Also of interest is Miller IBM Technical Disclosure Bulletin, 13, No. 3, p. 610 (August 1970), the disclosure of which is incorporated by reference herein, which discloses a ceramic body having internal channels.
Moulene et al. U.S. Pat. No. 5,034,688, the disclosure of which is incorporated by reference herein, discloses a temperature controlled platen for supporting, for example, a semiconductor wafer. The platen is made of ceramic and contains a cavity inside the platen. Inside the cavity is a spiral tube which can convey a fluid for heating or cooling the platen.
Bonde et al. U.S. Pat. No. 5,099,311, the disclosure of which is incorporated by reference herein, discloses a microchannel heat sink which consists of a microchannel layer and a manifold. A thermal fluid is circulated through the microchannels for cooling or heating, for example, an integrated circuit. Walpole et al. U.S. Pat. No. 5,099,910, the disclosure of which is incorporated by reference herein, is similar to Bonde et al. in that a microchannel heatsink is disclosed.
Bernhardt U.S. Pat. No. 5,218,515, the disclosure of which is incorporated by reference herein, discloses a microchannel heatsink permanently bonded to the back of a chip. A cooling fluid circulates through the microchannels to cool the chip.
Bertin et al. U.S. Pat. No. 5,506,753, the disclosure of which is incorporated by reference herein, discloses a plurality of stacked semiconductor devices wherein the backside of each contains grooves for cooling. The chips are stacked so that the grooved side of the chip is stacked against the active side of the next chip. A cooling fluid may be circulated within the grooves.
All of the above thermal apparatus are separate and apart from the substrate to which the semiconductor device is joined and provide no electrical function with respect to the semiconductor device.
It would be desirable to have a substrate which provides electrical function with respect to the semiconductor device and yet also provides improved cooling to handle the most rigorous cooling requirements for today's high heat-generating semiconductor devices.
Accordingly, it is a purpose of the present invention to have an improved substrate that provides both electrical function and cooling function with respect to a semiconductor device mounted on the substrate.
It is another purpose of the present invention to have an improved substrate that can handle the cooling requirements of high heat-generating semiconductor devices.
These and other purposes of the invention will become more apparent after referring to the following description considered in conjunction with the accompanying drawings.